#include <stdint.h>
//-----------------------------------------------------------------------------
// MurmurHash2, by Austin Appleby
// (public domain, cf. http://murmurhash.googlepages.com/)

// Note - This code makes a few assumptions about how your machine behaves -

// 1. We can read a 4-byte value from any address without crashing
// 2. sizeof(int) == 4

// And it has a few limitations -

// 1. It will not work incrementally.
// 2. It will not produce the same results on little-endian and big-endian
//    machines.
namespace oceanbase
{
  namespace common
  {
  
  uint32_t murmurhash2(const void *key, int32_t len, uint32_t seed)
  { 
    // 'm' and 'r' are mixing constants generated offline.
    // They're not really 'magic', they just happen to work well.
    const uint32_t m = 0x5bd1e995;
    const int32_t r = 24;
  
    // Initialize the hash to a 'random' value
    uint32_t h = seed ^ len;
  
    // Mix 4 bytes at a time into the hash
    const unsigned char *data = static_cast<const unsigned char *>(key);
  
    while (len >= 4)
    {
      uint32_t k = ((uint32_t)data[0]) | (((uint32_t)data[1])<<8) 
                   | (((uint32_t)data[2])<<16) | (((uint32_t)data[3])<<24);
      
      k *= m;
      k ^= k >> r;
      k *= m;
  
      h *= m;
      h ^= k;
  
      data += 4;
      len -= 4;
    }
  
    // Handle the last few bytes of the input array
    switch (len)
    {
      case 3: h ^= data[2] << 16;
      case 2: h ^= data[1] << 8;
      case 1: h ^= data[0];
              h *= m;
    };
  
    // Do a few final mixes of the hash to ensure the last few
    // bytes are well-incorporated.
    h ^= h >> 13;
    h *= m;
    h ^= h >> 15;
  
    return h;
  }
  
  uint32_t fnv_hash2(const void *key, int32_t len, uint32_t seed)
  {
    const int p=16777619;
    int32_t hash = (int32_t)2166136261L;
    const char *data = static_cast<const char *>(key);
    for(int32_t i = 0; i < len; i++)
    {
      hash = (hash ^ data[i]) * p;
    }
    hash += hash << 13;
    hash ^= hash >> 7;
    hash += hash << 3;
    hash ^= hash >> 17;
    hash += hash << 5;
    hash ^= seed;
    return hash;
  }
  
  }
}
